Necrotizing Skin and Soft Tissue Infections Flashcards
How does necrotizing sot tissue infection affect blood and vasculature
Inflammatory invasion of blood vessels leads to obliterative endarteritis and necrosis of blood vessel walls, leading to thrombosis.
What percentage of NSTI’s are polymicrobial?
70-80% show 3-4 organisms (gram negative, GP, anaerobes, and fungi)
What are the two most commonly cultured bacteria in NSTIs?
Bacteroides and Streptococcus, though almost always in polymicrobial disease
How often is no portal of bacterial entry identified in NSTIs?
Approximately 10% of cases
What conditions predispose to NSTIs?
DM, HIV/AIDS, alcohol abuse, PVD, immunosuppressants (steroids, cancer, and etc.), renal failure, cirrhosis, heart disease, old age, obesity, and malnutrition
What are some worrisome physical exam findings that may appear in NSTIs?
edema, ecchymosis, skin necrosis, bullae that become hemorrhagic, crepitus, cutaneous numbness, Dishwater pus (turbid-foul smelling, brown fluid from liquifactive necrosis of fascia and subcutaneous tissue)
What radiological tests can be helpful in diagnosing NSTIs?
CT and MRI (fascial thickening, fat infiltration, fluid collections, soft tissue gas, and muscle involvement), though CT underestimates and MRI over-estimates extent of disease
Are gram stain and tissue biopsy useful in NSTIs?
They may give definitive diagnosis, but should not delay management
How much does mortality increase with a delay of more than 24 hours in operative intervention in NSTIs?
Doubles
True/False: After thorough debridement, NSTI patients often dramatically improve, in regards to their systemic toxicity.
True - however, possible multiple trips to the OR, and meticulous medical management, including wound care, is necessary post operatively
What antibiotics are used in treating NSTIs?
Penicillin G (or ampicillin) for GPs like clostridia/enterococci/peptostreptococci, Vancomycin for GPs such as MRSA; Clindamycin (or metronidazole) for anaerobes; Gentamicin (or some aminoglycoside) for GNs. Occasionally, extended spectrum antibiotics are used in monotherapy regimen.
What (controversial) benefits have been reported with hyperbaric oxygen?
Increased O2 tension in tissues which cause antibacterial effect on anaerobes, decreased endotoxicity, increased leukocyte phagocytosis, increases antibiotic delivery, and increased fibroblast proliferation. NO survival benefit.
What is the range of mortality found in NSTIs?
10-80%, but most report 30-40%
What is the most consistent prognosticator of poor outcomes (more operations and higher mortality) in NSTIs?
Delay in diagnosis
